1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
/*
* HMAC_DRBG (SP800-90A)
* (C) 2014,2015,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_HMAC_DRBG_H__
#define BOTAN_HMAC_DRBG_H__
#include <botan/stateful_rng.h>
#include <botan/mac.h>
namespace Botan {
class Entropy_Sources;
/**
* HMAC_DRBG from NIST SP800-90A
*/
class BOTAN_PUBLIC_API(2,0) HMAC_DRBG final : public Stateful_RNG
{
public:
/**
* Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
*
* Automatic reseeding is disabled completely, as it has no access to
* any source for seed material.
*
* If a fork is detected, the RNG will be unable to reseed itself
* in response. In this case, an exception will be thrown rather
* than generating duplicated output.
*/
HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf);
/**
* Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
*
* Automatic reseeding from @p underlying_rng will take place after
* @p reseed_interval many requests or after a fork was detected.
*
* @param prf MAC to use as a PRF
* @param underlying_rng is a reference to some RNG which will be used
* to perform the periodic reseeding
* @param reseed_interval specifies a limit of how many times
* the RNG will be called before automatic reseeding is performed
* @param max_number_of_bytes_per_request requests that are in size higher
* than max_number_of_bytes_per_request are treated as if multiple single
* requests of max_number_of_bytes_per_request size had been made.
* In theory SP 800-90A requires that we reject any request for a DRBG
* output longer than max_number_of_bytes_per_request. To avoid inconveniencing
* the caller who wants an output larger than max_number_of_bytes_per_request,
* instead treat these requests as if multiple requests of
* max_number_of_bytes_per_request size had been made. NIST requires for
* HMAC_DRBG that every implementation set a value no more than 2**19 bits
* (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
* example every 512 bit automatic reseeding occurs.
*/
HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
RandomNumberGenerator& underlying_rng,
size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
size_t max_number_of_bytes_per_request = 64 * 1024);
/**
* Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
*
* Automatic reseeding from @p entropy_sources will take place after
* @p reseed_interval many requests or after a fork was detected.
*
* @param prf MAC to use as a PRF
* @param entropy_sources will be polled to perform reseeding periodically
* @param reseed_interval specifies a limit of how many times
* the RNG will be called before automatic reseeding is performed.
* @param max_number_of_bytes_per_request requests that are in size higher
* than max_number_of_bytes_per_request are treated as if multiple single
* requests of max_number_of_bytes_per_request size had been made.
* In theory SP 800-90A requires that we reject any request for a DRBG
* output longer than max_number_of_bytes_per_request. To avoid inconveniencing
* the caller who wants an output larger than max_number_of_bytes_per_request,
* instead treat these requests as if multiple requests of
* max_number_of_bytes_per_request size had been made. NIST requires for
* HMAC_DRBG that every implementation set a value no more than 2**19 bits
* (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
* example every 512 bit automatic reseeding occurs.
*/
HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
Entropy_Sources& entropy_sources,
size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
size_t max_number_of_bytes_per_request = 64 * 1024);
/**
* Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
*
* Automatic reseeding from @p underlying_rng and @p entropy_sources
* will take place after @p reseed_interval many requests or after
* a fork was detected.
*
* @param prf MAC to use as a PRF
* @param underlying_rng is a reference to some RNG which will be used
* to perform the periodic reseeding
* @param entropy_sources will be polled to perform reseeding periodically
* @param reseed_interval specifies a limit of how many times
* the RNG will be called before automatic reseeding is performed.
* @param max_number_of_bytes_per_request requests that are in size higher
* than max_number_of_bytes_per_request are treated as if multiple single
* requests of max_number_of_bytes_per_request size had been made.
* In theory SP 800-90A requires that we reject any request for a DRBG
* output longer than max_number_of_bytes_per_request. To avoid inconveniencing
* the caller who wants an output larger than max_number_of_bytes_per_request,
* instead treat these requests as if multiple requests of
* max_number_of_bytes_per_request size had been made. NIST requires for
* HMAC_DRBG that every implementation set a value no more than 2**19 bits
* (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
* example every 512 bit automatic reseeding occurs.
*/
HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
RandomNumberGenerator& underlying_rng,
Entropy_Sources& entropy_sources,
size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
size_t max_number_of_bytes_per_request = 64 * 1024);
/**
* Constructor taking a string for the hash
*/
HMAC_DRBG(const std::string& hmac_hash) :
Stateful_RNG(),
m_mac(MessageAuthenticationCode::create_or_throw("HMAC(" + hmac_hash + ")")),
m_max_number_of_bytes_per_request(64 * 1024)
{
clear();
}
std::string name() const override;
void clear() override;
void randomize(uint8_t output[], size_t output_len) override;
void randomize_with_input(uint8_t output[], size_t output_len,
const uint8_t input[], size_t input_len) override;
void add_entropy(const uint8_t input[], size_t input_len) override;
size_t security_level() const override;
size_t max_number_of_bytes_per_request() const override
{ return m_max_number_of_bytes_per_request; }
private:
void update(const uint8_t input[], size_t input_len);
std::unique_ptr<MessageAuthenticationCode> m_mac;
secure_vector<uint8_t> m_V;
const size_t m_max_number_of_bytes_per_request;
};
}
#endif
|
